1. Field of the Invention
The present invention relates to a hand operated chain block and, more particularly, to a hand operated chain block wherein a load sheave is rotationally driven by pulling a hand chain passing over a hand wheel, so as to wind up and down a load chain passing over the load sheave.
2. Description of the Prior Art
In general, a hand operated chain block of this type includes a load sheave supported between a pair of side plates via bearings; and a hand wheel for driving the load sheave through a drive shaft. The hand wheel is rotationally driven by pulling a hand chain passing over the hand wheel, to cause the load sheave to be rotationally driven, so as to wind up and down the load chain wound over the load sheave.
The load chain of unloading side, opposite to the loading side of the load chain suspending a load, is fixed at the end by a fixing pin between the pair of side plates. Further, in order to allow the load chain to smoothly pass over the load sheave to ensure smooth winding up and down operation, a generally semi-circular chain guide for guiding the load chain to be wound over the load sheave is provided around the load sheave between the pair of side plates, so as to lay over the load sheave. A chain split for guiding the load chain to be moved to and from the load sheave is provided under the load sheave.
For enabling the fixing pin for fixing the end of the load chain of unloading side to be easily assembled in between the pair of side plates, the fixing pin should be preferably inserted from the outside of any one of the two side plates at the last stage of assembly. On the other hand, at the last stage of assembly, the hand wheel, the gear cover and other components are already assembled in the chain block body, so the position for the fixing pin to be assembled is limited to a marginal portion around the each side plate.
If the fixing pin is located at an excessively inner position in the marginal portion around the each side plate, there is a fear that when the load chain of loading side is wound up, a chain link of the load chain of unloading side fixed to the fixing pin and a chain link of the load chain moving to the unloading side may contact with each other and become tangled, to hinder smooth winding operation.
On the other hand, if the fixing pin is located at an excessively outer position, then the side plates must be increased in width, and accordingly the chain block cannot be reduced in size. In addition to this, when a full length of the load chain of loading side is wound down, the load chain of unloading side is tensed between the fixing pin and the load sheave, to cause a problem that the load chain of unloading side tensed pushes up the chain guide to cause deformation of the chain guide.